title: Retinoic acid and Cyp26b1 are critical regulators of osteogenesis in the axial skeleton.
abstract: Retinoic acid (RA) plays important roles in diverse biological processes ranging from germ cell specification to limb patterning. RA ultimately exerts its effect in the nucleus, but how RA levels are being generated and maintained locally is less clear. Here, we have analyzed the zebrafish stocksteif mutant, which exhibits severe over-ossification of the entire vertebral column. stocksteif encodes cyp26b1, a cytochrome P450 member that metabolizes RA. The mutant is completely phenocopied by treating 4 dpf wild-type embryos with either RA or the pharmacological Cyp26 blocker R115866, thus identifying a previously unappreciated role for RA and cyp26b1 in osteogenesis of the vertebral column. Cyp26b1 is expressed within osteoblast cells, demonstrating that RA levels within these cells need to be tightly controlled. Furthermore, we have examined the effect of RA on osteoblasts in vivo. As numbers of osteoblasts do not change upon RA treatment, we suggest that RA causes increased activity of axial osteoblasts, ultimately resulting in defective skeletogenesis.
authors.affiliation: Hubrecht Institute, University Medical Centre Utrecht, 3584 CT Utrecht, The Netherlands.
authors.forename: Kirsten M
authors.initials: KM
authors.lastname: Spoorendonk
authors.forename: Josi
authors.initials: J
authors.lastname: Peterson-Maduro
authors.forename: Jörg
authors.initials: J
authors.lastname: Renn
authors.forename: Torsten
authors.initials: T
authors.lastname: Trowe
authors.forename: Sander
authors.initials: S
authors.lastname: Kranenbarg
authors.forename: Christoph
authors.initials: C
authors.lastname: Winkler
authors.forename: Stefan
authors.initials: S
authors.lastname: Schulte-Merker
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D004625:Embryo, Nonmammalian / Q000166:cytology / Q000196:embryology / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D015971:Gene Expression Regulation, Enzymologic; D051379:Mice; D009154:Mutation / Q000235:genetics; D009990:Oryzias; D010006:Osteoblasts / Q000166:cytology / Q000187:drug effects / Q000201:enzymology; D010012:Osteogenesis / Q000187:drug effects; D010641:Phenotype; D000072516:Retinoic Acid 4-Hydroxylase; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D014212:Tretinoin / Q000494:pharmacology*; D015027:Zebrafish / Q000196:embryology / Q000378:metabolism
chemical_list: D014157:Transcription Factors; D014212:Tretinoin; D003577:Cytochrome P-450 Enzyme System; D000072516:Retinoic Acid 4-Hydroxylase